Ancient salt layer beneath Queensland could store Australia's renewable energy

Beneath the red dust of outback Queensland lies a rock formation older than the dinosaurs. For sixty years, the Adavale Basin sat largely ignored—invisible at the surface, buried under other geological layers. Now scientists think it could solve one of Australia's most pressing energy problem: where to store renewable power at a scale that actually matters.

Australia is generating record amounts of solar and wind electricity. The problem is timing. When the sun blazes or wind gusts, the grid produces more power than it can use. When clouds roll in or the wind dies, the grid needs backup. Lithium-ion batteries help, but they're expensive and limited in capacity. You can store energy for hours that way. Storing it for days—at the scale of millions of homes—is something else entirely.

The answer, researchers believe, might lie not above ground but two to three kilometres below it.

Underground caverns as energy vaults

The Adavale Basin was first identified in 1958, yet geologists still call it under-explored. It sits buried beneath two other basins, part of the vast Great Artesian Basin—one of Earth's largest underground freshwater systems. Unlike dramatic cliff faces or exposed rock layers, the Adavale Basin leaves no trace at the surface. To understand what's down there, you have to drill.

Geoscience Australia completed a $31 million drilling campaign to find out. In November, they drilled a borehole roughly three kilometres deep—a depth record for the agency. From that single hole, they pulled out a continuous 976-metre rock core, more than 500 rock chip samples, and several groundwater samples.

At the centre of their attention is a thick layer of rock salt called the Boree Salt deposit. It's currently the only known salt layer in eastern Australia thick enough to store hydrogen deep underground. "You can dissolve that rock salt out, and you can store things within that dissolved cavern, like hydrogen gas or compressed air," Mitchell Bouma, Director at Geoscience Australia, told ABC News.

The concept sounds odd, but it's proven technology. Engineers inject water to dissolve part of the salt, pump out the salty brine, and are left with an empty chamber. That chamber becomes an underground storage vault.

Here's how it works as an energy system: when renewable electricity is abundant, hydrogen produced from that power gets pumped into the cavern. Later, when demand spikes, the hydrogen comes back to the surface and generates electricity. The cavern becomes a geological battery—one operating at a scale that surface technology can't yet match.

A single cavern in the Adavale Basin could potentially store around 6,000 tonnes of hydrogen. That's roughly 100 gigawatt hours of energy—equivalent to about 50 of Australia's largest grid-scale batteries combined. Some experts estimate that just a handful of such caverns could supply enough electricity to power around 20 million homes for a day, based on average Brisbane household demand.

Large hydrogen storage facilities have already operated overseas for decades. In Utah, a major project is building two salt caverns designed to hold 5,500 metric tonnes of hydrogen each. The Adavale Basin's potential suggests Australia could develop similar infrastructure—turning an ancient geological formation into the backbone of the nation's clean energy system.

The next phase involves more drilling, more data, and the slow work of turning geological possibility into engineering reality.